#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
#include<string.h>
#include<stdlib.h>

int comper(const void* a, const void* b)
{
    return (*(char*)a) - (*(char*)b);
}
int main() {
    char* result = (char*)malloc(sizeof(char) * 100);
    scanf("%s", result);
    int len = strlen(result);
    qsort(result, len, sizeof(char), comper);
    printf("%s", result);
    free(result);
    return 0;
}